Contact lenses have been manufactured and broadly distributed for decades. In a typical lens manufacturing process, rods of contact lens stock material are sliced into small blanks, disks, or buttons. Each button is then mounted into a collet on a lathe and turned to the desired specifications.
Generally, contact lenses fall within a relatively narrow range of diameters. This narrow range of lens diameters meant the industry typically used a limited range of sizes of contact lens stock material. With a limited range of stock sizes in use, the industry typically only needed manufacturing equipment configured to function on this narrow range of stock sizes.
Due to improvements in contact lens technology and driven by other various desires and benefits, larger diameter contact lenses are now being used. This advance in lens technology resulted in the need for a larger diameter lens stock and buttons. However, the presence of a larger lens stock poses a problem because the lathes in the industry are typically set up for smaller sizes of contact lens stock. Furthermore, machining larger diameter lens stock also poses a problem because larger diameter lens stock, especially lens stock made from material with high oxygen permeability, tends to experience a greater amount of flexure, which causes geometric distortion, than what typical sized lens stock experiences during machining.
A current solution to the lathe collet size problem provides for the manufacture and supply of buttons with an integral protrusion machined onto the blank. This concept is illustrated in FIG. 4. The blank's protrusion enables a typical lathe collet to hold onto the button. However, in order to machine the protrusion onto the blank, the blank must be cut longer and machined in an additional process. Furthermore, the added machining step significantly increases tool cost. Thus, the integrated protrusion is an inefficient solution.
Accordingly, there exists a need for a device that overcomes these and other shortcomings.